Pressure and time controlled gas lift valve



June 20, 1967 W, A DUDLEY 3,326,229

PRESSURE AND TIME CONTROLLED GAS LIFT VALVE Filed Aug. 5l, 1964 I5 Sheets-Sheet l wf Hmmm/g;

BYM f ff f June 20, 1967 w. A. DUDLEY 3,326,229

` PRESSURE AND TIME CONTROLLED GAS LIFT VALVE Filed Aug. 51, 1964 5 Sheetsheei 2 June 20, 1967 w. A. DUDLEY 3,326,229

PRESSURE AND TIME CONTROLLED @As LIFT VALVE Filed Aug. 3l, 1964 3 Sheets-Sheet ."5

76a' v gf 73 22 6:9 Jak /5/ N@ 37 /36 32 H Z0 25 f1 33 /6 l, W/ ///0/77 aa//e United States Pate 3,326,229 PRESSURE AND TIME CONTROLLED GAS LIFT VALVE William A. Dudley, Dallas, Tex., assignor to Merla Tool Corporation, Garland, Tex., a corporation of Texas Filed Aug. 31, 1964, Ser. No. 393,234 16 Claims. (Cl. 137-155) This invention relates to valves, and more particularly to gas lift valves.

In the early development of gas lift valves, differential valves were employed which were spring-loaded and opened in response to a predetermined diierential across the valve developed by casing pressure and tubing pressure.

In later years, gas lift valves were opened in response to casing pressure acting on a pressure-responsive area, and the time of injection controlled by timing equipment at the surface which controlled the period of time that gas would he injected into the casing.

The valves which open in response to tubing pressure have the advantage of opening when a suitable column of fluid is present in the tubing. However, they have the disadvantage of not opening and closing rapidly and tending to aerate the column of oil within the tubing. On the other hand, the type of valve which is casingcontrolled opens and closes rapidly in response to surface equipment and moves the oil up the tubing in a slug. Casing-sensitive valves assume that a suitable head of liquid is within the tubing. This assumption is not always true, as the well does not ow at a constant rate and from time to time the overall rate of ilow changes, thus necessitating resetting of the timing cycle. Of course, if the column of oil in the tubing be either too high or too low, the eciency of the injected gas is low.

By this invention there is provided a valve which snaps open and closed and which opens in response to tubing pressure. The opening of the valve is responsive to a diilerential between casing and tubing pressure, and the valve positively will not open in response to casing pressure alone.

There has also been provided a timing system in which the time of injection of gas into the well is controlled by a timer which is a part of the gas lift valve, to thus eliminate the necessity of surface timing control equipment. Thus, this invention provides a valve which is tubing-sensitive, opens and closes rapidly, and eliminates surface timers. In other words, the best features of the differential valve, casing-sensitive valve and time-cycle injection are combined in a single valve.

It is an object of this invention to provide a gas-lift system in which the injection time is positively controlled.

Another object is to provide a gas-lift system in which the injection time is controlled down in the well and surface timing equipment may be eliminated.

Another object is to provide a gas-lift valve which includes a timer to positively control the time cycle of gas injection through the valve.

Another object is to provide a gas-lift valve which prevents underloading or overloading of the injection gas.

Another object is to provide a pilot-operated tubingj sensitive valve in which the valve opens in response to tubing pressure and will not open in response to casing pressure alone.

Another object is to provide a gas-lift valve which snaps to full open and full close position, and which operates in response to tubing pressure reaching a selected value.

Another object is to provide a pilot-operated valve which includes a timer to positively control the time cycle of gas injection through the valve in which the valve is 3,326,229 Patented June 20, 1967 ICC opened in response to tubing pressure with a snap action and remains open until the time cycle is completed and then closes with a snap action.

Another object is to provide a time cycle control valve which is tubing-sensitive instead of casing-sensitive to combine the best features of tubing sensitivity and time cycle control of prior valves.

Another object is to provide a pilot-operated gas-lift valve which does not depend upon the casing or tubing pressure reaching selected values, but instead opens when tubing pressure rises to a selected value less than casing pressure.

Another object is to provide a pilot-operated tubingsensitive gas-lift valve in which the valve opens when the height of liquid in the tubing above the valve relative to the gas pressure available in the casing-tubing annulus is such that eiiicient lifting of the liquid will result.

Another object is to provide a tubing-sensitive, pilotoperated valve which closes when the tubing pressure is in excess of the casing pressure to prevent 'back-flow to the casing.

Another object is to provide a gas-lift valve which employs pressure-responsive members such as Belloframs wherein the pressure differential across the pressure-responsive member is very low under all conditions to thus prevent damage to the pressure-responsive member.

Another object is to provide a gas-lift valve which is capable of discriminating between a false tubing pressure signal and a true signal resulting from a column of iiuid standing in the tubing above the valve.

Other objects, features and advantages of the invention will be apparent from the drawings, the specification and the claims.

In the drawings, wherein an illustrative embodiment of this invention is shown, and wherein like reference numerals indicate like parts:

FIGURE 1 is a sectional view through a well system employing a plurality of valves constructed in accordance with this invention.

FIGURE 2 is a view partly in section, partly in elevation, and partly in phantom, showing the valve of this invention in a tubing in a well;

FIGURE 3 is a schematic view of a valve embodying this invention;

FIGURES 4A and 4B are views in vertical crosssection through a valve constructed in accordance with this invention, with FIGURE 4B being a continuation of FIGURE 4A and the topmost section of the Valve omitted; and,

' FIGURE 5 is a graph illustrating the operation of the valve shown in the drawings.

In accordance with this invention, a system is provided such as shown in FIGURE l in which all surface timing controls may be omitted. The tubing 10 is run Within the casing 11 and a packer 12 may be set in the casing-tubing annulus above the producing formation 13. A plurality of valves 14 are provided in the tubing. While the illustrated valves are of the wireline type, it will be understood that they may be placed in the well at any time and in any desired manner.

Each valve is tubing sensitive and includes a mechanism which opens the valve when the tubing pressure is a selected value below casing pressure. If tubing pressure is greater than casing pressure, the valve will be closed. After a valve opens, a timing mechanism controls the time during which the valve remains open. The main valve opens and closes with a snap action.

The Well will be unloaded in the conventional manner by U-tubing Huid through the several gas-lift valves beginning with the upper valve and proceeeding successively down the string of valves.

While these valves may be utilized as working valves and other valves utilized as unloading valves, it is preferred that valves of the instant invention be utilized at all depths where working valves are required.

As is well known to those skilled in the art, -a well may produce through several progressively lower positioned valves during its life, and the production valves should preferably be valves constructed in accordance with this invention so that all production will be timed down in the well.

Reference is now made to FIGURE 3 which shows schematically the principle of operation of the illustrative form of valve. The valve includes a housing having spaced seals 16 and 17 which are adapted to sealingly engage a side pocket mandrel of the form shown in FIG- URE 2. The valve includes a passageway provided by chambers 18a and 18b and when the valve is open, gas enters through inlets 19 at the beginning of the passageway and exits through outlets 21 at the end of the passageway in the conventional manner.

The valve is shown as a pilot-operated valve, and a motor 22 is provided for controlling movement of the valve member 23 toward and away from its seat 2t) in the conventional manner. The motor piston 22 is provided with a sliding seal 22a engaging the wall of the housing. Casing gas passes upwardly through the back-check valve passageway 24 and into the chamber 25. From the explanation thus far given, it will be appreciated that when the main valve 23 is closed the motor piston is subjected to casing pressure on both sides as is conventional with many pilot-operated valves. The back-check passageway 24 provides a bleed or restricted flow path and, when the pressure in chamber 25 is reduced, the main valve opens. Upon the pressure in chamber 25 returning to casing pressure, the main valve will again close. This form of operation of the main valve member and motor piston is well known in the pilot valve art.

In order to provide trigger operation of the timing cycle and opening of the main valve for a specified length of time, there is provided a pressure-responsive member which may take the form of piston 26 provided with an O-ring 27 slidably engaged with housing 15. Above the uppermost packing 16, and thus exposed to tubing pressure, is a port 28. This port exposes the upper surface of the piston 26 to tubing pressure. Thus, the piston 26 is exposed on its upper surface to tubing pressure and on its lower surface to casing pressure. When the combined force exerted by tubing pressure and spring 29 on the pist-on 16 exceeds the force exerted by casing pressure in chamber 25, the piston 26 moves downwardly and triggers the beginning of the cycle by unseating ball valve 31 from its seat 32 on the lower end of communicator tube 33.

Upon unseating of ball 31 there begins a sensing cycle in which the valve senses whether or not the signal in the tubing is caused by a head of uid above the valve or by a false signal. An example of a false signal would be a slug of liquid being lifted through the tubing by gas injected through a lower valve. Where a false signal is received, the main valve 23 remains closed.

The signal-sensing system is designed to require that the tubing pressure signal be present for a finite length of time before the casing pressure in chamber 25 is reduced to tubing pressure to permit upward movement of the motor 22. In order to accomplish this, gas rising through the communicator tube 33 passes into chamber 34 and is effective on pressure-responsive member 35. The gas must move the pressure-responsive member 35 from a first position, in which casing pressure is maintained in chamber 25, to a second position in which the chamber 25 is vented to tubing pressure.

In order to give the system time to sense the tubing signal, means are provided to control the rate of movement of pressure-responsive member 35. Preferably, upward movement of the pressure-responsive member 35 is resisted by a body of liquid in the chamber 36 which must be moved through a rate control means 37. Chamber 36 forms a portion of a pressure chamber lilled with incompressible uid. This means for controlling the rate of movement of pressure-responsive member 35 may take any form. In the illustrative embodiment it is provided by the needle valve-controlled orilice 37. The needle valve 38 is adjusted so that the injection cycle of the valves below is shorter than the time required for pressureresponsive member 35 to force the fluid through the rate means and reach its second position. If the tubing signal reduces before this time, the tubing pressure entering through port 28 will reduce and the casing pressure will move pressure-responsive member 26 up to seat valve 31 and stop the cycle.

Assuming that the signal is a true signal, the pressureresponsive member 35 moves upwardly until a shoulder 39 on the pressure-responsive member engages a shoulder 41 on the upper end of communicator tube 33. When this occurs, the tube is raised. It will be noted that at an intermediate point the tube is provided with a pilot valve 42 in seat 43. When the tube is raised and the valve 42 leaves its seat, the Chamber 34 below the pressure-responsive member 35 is let into communication with the chamber 45 above the pressure-responsive member 26. At this time, casing pressure in chamber 25 flows through communicator tube 33, thence to chamber 34, through valve seat 43, to chamber 45, and out port 28 to the tubing. In this manner, the pressure above the motor piston 22 is reduced and the main valve is opened. Passageway 24 is smaller in size than all downstream passageways and provides a pressure drop.

Means are provided for controlling the rate of movement of the pressure-responsive member 35 downwardly to control the time during which gas will be injected. As this pressure-responsive member 35 moves downwardly, a shoulder 46 will engage the top of communicator tube 33 due to the action of spring 47. Upon the pressureresponsive member moving back to its first position, the valve 42 will again engage seat 43 blocking the ow of gas from chamber 34 into chamber 45. When this occurs, pressure will begin to build up in chamber 25 above the motor piston 22. This pressure will move the trigger valve 31 onto its seat and will seat the main valve. At this time, the tubing pressure will be dropping and the casing pressure will be sufficient to move the pressure-responsive member 26 upwardly with valve 31 on its seat to again unseat valve 42 and permit the pressure within chamber 34 under the pressure-responsive member 35 to reduce toward tubing pressure.

The rate of movement of the pressure-responsive member 35 is preferably controlled by movement of liquid through the partition 48. In addition to the pathway provided by the bleed 37, an additional needle Valve-controlled passage 49 is provided. This passage is controlled by a check valve 51 so that it only permits vmovement of uid from the -chamber 52, which with chamber 36 provides the pressure chamber filled with incompressible fluid.

Another pressure-responsive member 53, which may be a Bellofram, forms a wall of the chamber 52 and tubing pressure is admitted through ports 54 to the upper face of this pressure-responsive member 53. The two pressure-responsive members 35 and 53 have the same effective pressure-responsive area, and therefore when the valve 42 is unseated to reduce the pressure in chamber 34 to tubing pressure, the same amount of pressure acts upwardly on the low Bellofram 35 and downwardly on the upper Bellofra'm 53, `and thus pressure on the fluid in the pressure chamber is balanced.

In order to move the lower Bellofram 35 downwardly, suitable resilient means are provided. Preferably, a pair of springs 55 and 56 urge Bellofrarns 53 and 35 downwardly. The combined force is exerted in a direction to move the lower Bellofram 35 downwardly to seat the valve 42. While a single spring could be utilized, a pair of springs, one acting on each Bellofram, is used so that the Belloframs will have equal life, as will be explained hereinbelow.

As mentioned above, upon reseating of valve 42, casing pressure builds up in chamber 34 until valve 31 seats. This positions the parts in the same position as when a false signal is sensed. At this time, the tubing pressure within chamber 45 would drop to a value below that which, with the force exerted by spring 29, would balance the force of casing pressure in chamber 25. This unbalance across the pressure-responsive member 26 would result in the pressure-responsive member moving upward to unseat valve 42 and return the pressure in chamber 34 to tubing pressure. Just before the tubing pressure reaches an amount suficient to move the piston 26 downwardly and unseat ball 31, the valve would return to the position illustrated in FIGURE 3 with the valve 42 seated to commence a cycle of operation as hereinabove explained.

Referring now to FIGURES 2, 4A and 4B, the preferred form of valve is shown. The upper end of body 15 terminates in a wireline shing neck 57 for running an-d retrieving the valve in the usual manner. It will 'be noted that tubing is provided with a conventional side pocket 58 having inlet port 59 and outlet port 61. The valve is run in the side pocket with the seals 16 and 17 sealingly engaging the side pocket in the customary manner. It will be noted that the ports 28 and 54 are located to have clear access to tubing pressure.

The body indicated generally at includes the top closure 60 (the upper extremity of which is shown in FIGURE l). A partition sub 48a which includes the partition 48 depends from the top closure 60. A control valve sub 61 depends from the partiti-on sub. Continuing down the body, a motor valve sub 62 is secured to the lower end of the cont-rol valve sub. Secured to the lower end of the motor valve sub 62 is a main valve sub 63. The remainder of the valve body is made up Iof packing sub 64 and a lower closure 65.

A main gas passageway is provided through the valve by the inlet 19, the passageway section 18a above the valve, the passageway section 18b below the valve, and

- the outlet 21. The inlet 19 is protected against trash by a suitable screen 66.

The valve member 23 cooperates with Valve seat 20 in the passageway to control the How through the valve.

Opening and closing of the main valve 23 is controlled by the motor piston 22. This piston is connected to the main valve by a valve stem 67. This stem has a passageway 68 therethrough which includes the bleed section 24. Reverse tlow through this bleed section is prevented by the check valve 69.

The motor is an improvement over the motor shown in the co-pending application of Lamb and Dudley Ser. No. 170,593, to which reference is made for a complete discussion of the motor. This valve follows generally the teaching of the Lamb and Dudley valve, but makes provision for sealing in both directions to prevent tiow past the motor piston when the tubing pressure is greater .than casing pressure. The valve stem 67 includes a stop 69 at its upper end against which a Wedge member 71 .may abut. The Wedge member has a sliding seal with the piston provided by O-ring 72. The wedge member has a frusto-conical outer periphery 73 which cooperates with the inner wall of the annular seal member 22a. The seal member has an inner wall conforming to surface 73 and an outer cylindrical wall to engage cylinder 77.

Below the annular seal member 22a a seal stop 74 is provided on the valve stem. At the top of the piston, means are provided for urging the Wedge downwardly. This means includes a spring 75 and a washer 76 which has a depending flange 76a engaging the upper surface of the wedge member 71.

While the main valve 23 is closed, casing pressure is present on both sides of the motor. When the pressure in chamber 25 is reduced to tubing pressure, the casing pressure acts on the lower end of the annular seal 22a forcing it upwardly against the wedge 71 which in turn is held against movement by the stop 69. It is noted that the wedge at its upper end has a maximum diameter which is substantially less than the diameter of the cylinder 77 with which the outer cylindrical wall of the seal cooperates to provide a space in which the seal is unsupported. This permits free movement of the annular seal along the wedge 79. The seal is made of polytetrafluroethylene. The advantages of the use of this material are fully explained in the Lamb-Dudley application, and include a low coeticient of friction, ability to withstand high temperature and chemicals normally found in oil Wells. Additionally, this material will mechanically absorb small particles by imbedding and will absorb impact without permanent deformation.

In the event tubing pressure is greater than casing pressure, the seal 22a will move down and engage stop 74. Pressure acting on the wedge ring and spring 75 will force the wedge ring down to engage the seal and wedge it rmly against the cylinder 77 to seal against pressure in this direction.

When the main valve is unseated, it opens with a snap action due to the bottom of the main valve 23 being suddenly exposed to casing pressure. The upward velocity is substantial and, to avoid damage, a buffer assembly indicated generally at 78 is provided. This assembly includes several sections of resilient material 79 separated by metal plates 81. By separating the resilient material and permitting each to act individually, it has been found that greater impact can be absorbed by a given body of material. The assembly includes a retainer 82 having a lower flange 82a which supports the bumper rubbers and plates against the shoulder 83 in sub 62. The entire assembly is held against the shoulder 83 by the spring 75.

In addition to holding the shoulder assembly in place, and holding the wedge 71 in contact with the annular seal 22a for reverse sealing, the spring 75 also functions to return the main valve to its seat when pressure across the motor 22 is equalized. Thus, spring 75 is a triple purpose spring.

Reference is now made to the means for opening and closing the main valve by controlling the pressure across the motor 22. This means in the form of valve illustrated includes the trigger means for initiating the cycle. Piston 26 has a sliding seal with the sub 62 in the form of an O-ring 27. A seal is also provided with the communicator tube 33 by an O-ring 84. Depending from the pressureresponsive member 26 are a plurality of stop lugs 85 which engage the shoulder 86 and limit downward movement of the pressure-responsive member or piston 26. The members are spaced apart and have secured thereto as by welding the ball valve 31 which engages seat 32 at the lower end of communicator tube 33. The spring 29v urges the piston 26 downwardly and, when the combined force of spring 29 and tubing pressure exceeds casing pressure, the piston 26 moves down to unseat ball 31 and admit casing pressure into the chamber 34.

Casing pressure is held in chamber 34 by a check valve 87. This valve insures that tubing pressure will always be present in chamber 34 to protect the Bellofram 35.

The means for opening and closing the main valve 23 includes the pilot valve member or control valve member 42 formed on an intermediate section of the communicator tube 33. This valve cooperates with seat 43 to control the pressure within chamber 25.

The upper end of the communicator tube 33 is provided by a spring housing 33a which contains the spring 47. The upper end of the spring housing has the flange 41 thereon for engagement by flange 39 to unseat the control valve 42.

The pressure-responsive member 35 is shown to be formed by a Bellofram. This form of pressure-responsive member is selected for its ability to permit substantial travel. One end of the Bellofram is clamped between the subs 48a and 61 and the other end is clamped between two parts 88 Iand 89 which provide a Bellofram closure and are part of the pressure-responsive member. The part 88 has a bore 91 for receiving the upper end 33a of the communicator tube and carries the shoulder 46 against which the tube abuts when the control valve 42 is off its seat. Additionally, the upper section 88a of this part has an annular slot 92 to support and guide spring 56. The outer periphery of this part 88a provides a support for the Bellofram 35. A suitable closure 93 makes the assembly pressure-tight. Thus, casing pressure in chamber 34 may move the pressureresponsive member 35 upwardly to unseat valve 42 and open the main valve.

The means for controlling the rate of travel of pressureresponsive member 35 includes the partition 48 having a bleed passage 37 therethrough. This passage is controlled by the adjustable needle valve 3S. The adjustment of this bleed should ybe such that more time is required for liquid within chamber 36 to pass through the bleed passage 37 than is required for any valve therebelow to complete its injection cycle, that is, from the time the main valve opens until the main valve closes. This insures that the instant valve will not open in response to a false signal.

Also located in the partition sub is the passageway 49 controlled by the back-check 51 and needle valve 94. The back-check 51 makes this passageway inactive while fluid is being transferred from chamber 36 to chamber 52. However, upon the return of this fluid both passageways 37 and 49 are utilized and an additional adjustment is provided by needle valve 94 to permit adjustment of the injection time.

The upper pressure-responsive member 53 is also preferably a Bellofram held between the sub 48a and top closure 60. The free end of the Bellofram is clamped between the spring guide 95 and clamp 96. A seal 97, annular in form, is carried by the clamp 96 and surrounds the two passageways 37 and 49 to limit ow of uid and downward movement of the upper Bellofram.

It might be noted that the spring 55, which is exposed to well fluids, is longer than spring 56 which is in an isolated chamber. This is due to the fact that different materials should be used in the springs to prevent weakening of the upper spring due to various substances present in the well. Preferably, the two springs have the same spring rate and exert the same force so that the same diierential may be present across the two Belloframs, and they will have a substantially equal life.

Considering now the operation of the valve in detail, it will be assumed that a pressure of 1,000 pounds is present in the casing and a much lower pressure is present in the tubing. We can further assume that the area of the piston 26 is such that casing pressure will exert an upward force of 500 pounds across the piston. We may further assume that the spring 29 exerts a force of 150 pounds and that a tubing pressure of 700 pounds would result in a downward force across the piston 26 of 350 pounds. Thus under the assumed pressure conditions, tubing pressure of 700 pounds is required to unseat ball 31. If we now assume that a valve below is the working valve, and the valve under consideration is an unloading valve, it will be appreciated that each time the working valve admits gas a false signal will be sensed by each of the unloading valves. As gas is admitted to the tubing below `and the column of Huid rises in the tubing, the pressure on piston 26 will increase. In the event this pressure is sumcient to overbalance the force of casing pressure, ball 31 will unseat and casing pressure will rise through bleed 24 and chamber 25 to the communicator tube 33, and thence through outlets 9S in the -communicator tube into the chamber 34 and be effective on the lower Bellofram 35. The ball 31 will snap full open due to casing pressure becoming effective on the top ofthe ball.

The lower pressure-responsive member 35 will begin to rise at the rate controlled by the setting of the needle valve 38. This rise will be opposed by tubing pressure presen-t on the upper pressure-responsive member 53 through ports 54. As the ltwo pressure-responsive members are preferably of equal area, the driving force is the dilerential between the two pressures. Before the lower pressure-responsive member has reached a position in which ange 39 will engage flange 41, the slug of uid rsing in the tubing will have passed and the tubing pres sure will yfall off. As the pressure reduces, the piston 26 rises and reseats valve 31. This stops further upward movement of the two Bellorams. As tubing pressure further reduces, the casing pressure effective across the piston 26 and the area of the communicator tube 33 exerts a torce greater than the tubing pressure and the piston 26 and ball 31 travel upwardly together. This unseats pilot control valve 42. Ball 31 will remain seated because of ared seat 32 providing an area exposed to casing pressure acting downwardly. With the control valve 42 unseated, the casing pressure in chamber 34 quickly reduces to tubing pressure and springs 55 and 56 return the Belloframs either to the position lillustrated in the drawings, or near this position, depending upon tubing pressure. In any event, as tubing pressure rises to approach 700 pounds, this .pressure and the spring 29 will lmove the piston 26 and ball 31 downwardly and the springs 55 and 56 will force the lower Bellotram 35 downwardly until the valve 42 seats. In this manner, a false signal will not result in opening of a valve.

lf we assume that the valve is a working valve, and the signal is caused by a head of fluid standing in the tube above the valve, then the action described is the same except that the piston 26 stays in its down position and the Belloframs continue to move upwardly together. As the Bellofram moves upwardly from the position shown to the valve-opening position, the shoulder 39 engages shoulder 41 and lifts valve 42 from its seat 43. The spring 47 snaps the control valve to fully open position where the flange 41 is against the shoulder 46. When this occurs, pressure in chambers 34, 45 and 25 are reduced to tubing pressure because the bleed 24 is the smallest opening 4for flo-w of fluid from the casing through these chambers. The two springs 55 and 56, which preferably exert about a '3U-pound force each, now begin to move the two Belloframs downwardly and torce the liquid through the two passageways 37 and 49.

At the time that fluid in chamber 25 was reduced to tubing pressure, the motor 22 snapped the main valve off of its seat and the valve began the injection of gas into the tubing. The two Belloframs move downwardly at a controlled rate to permit the desired time of injection of casing gas into the tubing to pass. When this time has elapsed, the lower Bellofram seats the control valve 42 on its seat and casing pressure begins to build up in chamber 25 as well as in chamber 34. As pressure in chamber 25 moves the main valve 23 toward its seat, a differential begins to build up and the force of uid rushing past the main valve snaps it to closed position.

This buildup of pressure in chamber 25 moves the piston 26 upwardly until the valve 31 engages its seat 32. In the meanwhile, casing pressure in chamber 34 has raised the Belloframs. However, tubing pressure is continuing to drop and will be low enough relative to casing pressure that the ball 31 and piston 26 will both move upwardly to unseat valve 42 again. At this time, casing pressure will exhaust from the chamber 34 and the Belloframs will slowly descend. As in the case of the false signal, the control valve 42 may seat or it may remain olf its seat until tubing pressure builds up again to a value close to 700 pounds.

It might be noted that the arrangement of the two Belloframs and their associated structure, together with the rate control means, is such that the differential across the Bellotrams will always be small. If we assume that a pressure of 700 pounds is present in the tubing and 1,000 pounds in the casing, there is present a total of 300 pounds dilerence. lf each of the springs 55 and 56 exerts a force which is equal to 50 pounds of pressure, and the rate control means provides a 20D-pound differential, then the pressures across the Belloframs are as follows: Below Bellofram 35, 1,000 pounds opposes 950 pounds in chamber 36. Due to the pressure drop across needle valve 38 of 200 pounds, the pressure in chamber 52 below the Bellofram is 750 pounds. Thus, the pressure differential across the two Belloframs will be 50 pounds each.

It might be noted that to further protect the Belloframs, the arrangement is preferably such that valve 42 is seated while the spring 55 still exerts its design force. This force will slightly collapse the Bellofram 35 and permit the downward movement of the upper Bellofram until the seal 97 engages partition 48. This arrangement is preferred to insure that the valve 42 will be fully seated before downward movement of the upper pressure-responsive member is arrested.

The Belloframs are protected against excessively high pressure and the valve will not permit backflow of pressure. If we assume pressure to rise in the tubing to a value substantially equal to casing pressure, the valve will, of course, be open but stymied because no flow from casing to tubing will take place. However, when tubing pressure exceeds casing pressure, the tubing pressure will hold ball 31 off its seat and the higher tubing pressure will be effective on the motor 22 to hold the main valve seated. This will result because tubing pressure will be free to bypass check valve 87 and pass down through the tube 33 to be effective in chamber 25. As this tubing pressure will be equally effective on the two Belloframs with the incompressible liquid therebetween, the Bell-oframs will be protected against excessive pressures.

Reference is now made to FIGURE which illustrates the ability of the valve to open when the selected casing- .tubing pressure differential is present. Preferably, well fluids should be lifted when ltubing pressure is in the neighborhood of 60% to 80% of the available casing gas pressure. Referring to the graph, the point 100 represents the unseating of valve 31 with relative tubing pressure and casing pressure as illustrated. The legend time delay indicates the movement of the lower Bellofram from closed to control pilot valve open position. At this time, the tubing pressure rises almost instantaneously and injection time represents the time when the main valve is open and gas is being injected. It Will be noted that casing pressure drops during this time as indicated at 101. Upon valve 42 closing, tubing pressure falls off immediately as illustrated by the curve 1012, and gas pressure rises as shown at 103. In the illustration, it is assumed that gas pressure rises to a higher value as indicated at 104. lnasmuch as the valve operates on a selected differential, the tubing pressure rises past the point where it previously began the operation of the cycle to a new trigger pressure point 105 which is a greater tubing pressure .than that represented by point 100. Again, the same time delay occurs and tubing pressure rises almost instantaneously and is present during the predetermined injection time.

From a study of the graph, it will be apparent that the time cycle is begun at the time that tubing pressure rises to within a selected value of casing pressure. This means .that unloading will always occur when the tubing pressure is at a selected pressure less than casing pressure and the efficiency of the system will remain high. It will be appreciated from FIGURE 4 that the system cannot overload or underload, thus wasting gas. The system does not depend on a clock at the surface for injecting gas periodically, but injects gas only when needed because the timer is in the well and is not responsive to time but is responsive to a suitable column of oil being present in the tubing.

The foregoing disclosure and description ofthe invention is illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made Within the scope of the appended claims without departing from the spirit of the invention. What is claimed is:

1. A valve comprising;

a body having an inlet and an outlet interconnected by a passageway;

main valve means controlling flow through said passage- Way;

pressure-responsive motor means controlling opening and closing of said main valve means;

and time control means governing operation of the motor means including,

a pressure-responsive member having opposed pressure-responsive surfaces, one of said surfaces being continuously exposed to outlet pressure,

means for controlling the rate of movement of said pressure-responsive member,

resilient means urging said pressure-responsive member in one direction,

trigger valve means operable in response to outlet pressure rising to a selected value and exposing said pressure-responsive member to inlet pressure on the other surface,

control valve means operable in response to movement of said pressure-responsive member to a selected position by said inlet pressure for reducing the pressure on said other surface of the pressure-responsive member to outlet pressure and changing the pressure conditions effective on the motor means to open the main valve means and operable in response to movement of said pressure responsive member to a second selected position by said resilient means for restoring the original pressure conditions effective on the motor means to close the main valve means.

2. A valve comprising a body having an inlet and an outlet interconnected by a passageway;

main valve means controlling flow through said passage- Way;

pressure responsive motor means controlling opening and closing of said main valve means;

and time control means governing operation of the motor means including;

a pressure responsive member,

resilient means urging said pressure responsive member in one direction, means controlling the rate of movement of said pressure-responsive member and providing different rates with the faster rate being in effect when the resilient means is moving the pressure-responsive member,

means including a bleed passageway for conducting inlet pressure to said pressure responsive member,

control valve means operable in response to movement of said pressure responsive member to a selected position by inlet pressure for reducing the pressure on the pressure responsive member to outlet pressure and changing the pressure conditions effective on the motor means to open the main valve means and operable in response to movement of said pressure responsive member to a second selected position by said resilient means for restoring the original pressure conditions effective on the motor means to close the main valve means.

3. A valve comprising a body having an inlet and an outlet interconnected by a passageway;

main valve means controlling ow through said passageway; pressure responsive motor means controlling opening and closing of said main valve means;

and time control means governing operation of the motor means including;

a first pressure responsive member,

means for controlling the rate of movement of said pressure responsive member,

resilient means urging said pressure responsive member in one direction,

a second pressure responsive member exposed on opposite sides to inlet and outlet pressure,

trigger valve means operable in response to a selected differential across said second pressure responsive member for exposing said first pressure responsive member to inlet pressure,

control valve means operable in response to movement of said first pressure responsive member to a selected position by inlet pressure for reducing the pressure on the first pressure responsive member to outlet pressure and changing the pressure conditions effective on the motor means to open the main valve means and operable in response to movement of said rst pressure responsive member to a second selected position by said resilient means for restoring the original pressure conditions effective on the motor means to close the main valve means.

4. The valve of claim 1 wherein the rate controlling means provides different rates with the faster rate being in effect when the resilient means is moving the pressure responsive member.

5. The valve of claim 1 wherein the rate controlling means includes a pair of bleed passageways both of which are effective when the resilient means is moving the pressure responsive member and only one of which is effective when the pressure responsive member is moving against the resilient means.

6. A valve comprising;

a body having an inlet and an outlet interconnected by a passageway;

main valve means controlling fiow through said passageway;

pressure responsive motor means controlling opening and closing of said main valve means;

and time control means governing operation of the motor means including;

a chamber filled with incompressible uid and having first and second spaced pressure responsive members,

said first pressure responsive member continuously exposed to outlet pressure,

resilient means urging said pressure responsive members in one direction,

means controlling the rate of flow of fiuid in said chamber upon vmovement of said pressure responsive members,

a third pressure responsive member exposed on opposite sides to inlet and outlet pressures,

trigger valve means operable in response to a selected differential across said third pressure responsive member for exposing said second pressure responsive member to inlet pressure,

control valve means operable in response to movernent of said second pressure responsive member to a selected position by inlet pressure for reducing the pressure on the second pressure responsive member to outlet pressure and changing the pressure conditions effective on the motor means to open the meain valve means,

said control valve means operable in response to movement of said second pressure responsive member to a second selected position by said resilient means for restoring the original pressure conditions effective on the motor means to close the main valve means.

7. A valve comprising,

a body having an inlet and an outlet interconnected by a passageway,

main valve means controlling flow through said passageway,

a chamber filled with incompressible fluid and having first and second pressure responsive members,

a pair of resilient means each biasing a pressure responsive member in a direction to exert a cumulative force moving fluid through said rate control means, means controlling the rate of flow of said uid between said pressure responsive members and effecting a pressure drop across said means upon movement of said pressure responsive member, said rate-controlling means providing different rates with the faster rate being in effect when the resilient means is moving the pressure responsive members,

said first pressure responsive member exposed to outlet pressure,

means selectively exposing said second pressure responsive member to inlet pressure to move said second pressure responsive member from a first to a second position and open said main valve upon said second pressure responsive member reaching said second position, said last mentioned means reducing the pressure on said second pressure responsive member to outlet pressure when it reaches said second position and closing said main valve upon said resilient means returning said second pressure responsive member to said first position.

8. The valve of claim 6 wherein the rate controlling means provides different rates with the faster rate being in effect when the resilient means is moving the pressure responsive members.

9. The valve of claim 6 wherein the rate controlling means includes a pair of bleed passageways both of which are effective when the resilient means is moving the pressure responsive members and only one of which is effective when the pressure responsive members are moving against the resilient means.

10. A valve comprising;

a body having an inlet and an outlet interconnected by a passageway;

main valve means controlling fiow through said passageway;

pressure responsive motor means controlling opening and closing of said main valve means;

and time control means governing operation of the motor means including;

a chamber filled with incompressible fluid and having first and second spaced pressure responsive members,

said first pressure responsive member continuously exposed to outlet pressure,

resilient means urging said pressure responsive members in one direction,

means controlling the rate of fiow of iiuid in said chamber upon movement of said pressure responsive members,

a thir-d pressure responsive member exposed on opposite sides to inlet and outlet pressures,

trigger valve means operable in response to a selected differential across said third pressure responsive member for exposing said second pressure responsive member to inlet pressure,

control valve means having a loss motion connection with said second pressure responsive member biased toward collapsed position and operable in response to movement of said second pressure responsive member to a selected position by inlet pressure for reducing the pressure on the second pressure responsive member to outlet pressure and changing the pressure conditions effective on the motor means to open the main valve means,

.said control valve means operable in response to 13 movement of said second pressure responsive member to a second selected position by said resilient means for restoring the original pressure conditions effective on the motor means to close the main valve means. 11. A valve comprising; a body having an inlet and an outlet interconnected by a passageway; main valve means controlling flow through said passageway; pressure responsive motor means controlling opening and closing of said main valve means; and time control means governing oper-ation of the motor means including;

a chamber lled with incompressible fluid and having rst and second spaced pressure responsive members,

said rst pressure responsive member continuously exposed to outlet pressure,

resilient means urging said pressure responsive members in one direction,

means controlling the rate of flow of fluid in said chamber upon movement of said pressure responsive members,

a third pressure responsive member exposed on opposite sides to inlet and outlet pressures,

resilient means urging said third pressure responsive member toward its inlet pressure side,

trigger valve means operable in response to a selected differential across said third pressure responsive member for exposing said second pressure responsive member to inlet pressure,

control valve means having a loss motion connection with said second pressure responsive member biased toward collapsed position and operable in response to movement of said second pressure responsive member to a selected position by inlet pressure for reducing the pressure on the second pressure responsive member to outlet pressure and changing the pressure conditions effective on the motor means to open the main valve means,

said control valve means operable in response to movement of said second pressure responsive member to a second selected position by said resilient means for restoring the original pressure conditions effective on the motor means to close the main valve means.

12. In a gas lift valve having a main valve member controlling flow through the valve,

pressure-responsive motor means controlling opening and closing of the main valve member in response to changes in pressure diierential thereacross,

a resiliently biased pressure-responsive member continuously subjected to downstream pressure on one side,

a pilot Valve carried by the resiliently biased pressureresponsive member and controlling the pressure differential across the motor means,

the improvement which comprises the provision of means for subjecting the other side of pressure-responsive member to upstream pressure in response to downstream pressure increasing to a selected value.

13. The valve of claim 2 wherein the rate-controlling means includes a pair of bleed passageways both of which are eifective when the resilient means is moving the pressure-responsive member and only one of which is eiTective when the pressure-responsive member is moving against the resilient means.

14. The valve of claim 3 wherein the rate-controlling means provides diierent rates with the faster rate being in effect when the resilient means is moving the pressureresponsive member.

15. The valve of claim 3 wherein the rate-controlling means includes a pair of bleed passageways both of which are effective when the resilient means is moving the pressure-responsive member and only one of which is eiective when the pressure-responsive member is moving against the resilient means.

16. The valve of claim 7 wherein the rate-controlling means includes a pair of bleed passageways both of which are effective when the resilient means is moving the pressure-responsive members and only one of which is effective when the pressure-responsive members are moving against the resilient means.

References Cited UNITED STATES PATENTS 2,600,073 6/1952 Plank 251-29 X 3,077,894 2/1963 Cummings 137-155 3,175,514 3/1965 McMurry 137-155 X 3,213,806 10/1965 Walton 103-232 ALAN COHAN, Primary Examiner. 

12. IN A GAS LIFT VALVE HAVING A MAIN VALVE MEMBER CONTROLLING FLOW THROUGH THE VALVE, PRESSURE-RESPONSIVE MOTOR MEANS CONTROLLING OPENING AND CLOSING OF THE MAIN VALVE MEMBER IN RESPONSE TO CHANGES IN PRESSURE DIFFERENTIAL THEREACROSS, A RESILIENTLY BIASED PRESSURE-RESPONSIVE MEMBER CONTINUOUSLY SUBJECTED TO DOWNSTREAM PRESSURE ON ONE SIDE, A PILOT VALVE CARRIES BY THE RESILIENTLY BIASED PRESSURE RESPONSIVE MEMBER AND CONTROLLING THE PRESSURE DIFFERENTIAL ACROSS THE MOTOR MEANS, THE IMPROVEMENT WHICH COMPRISES THE PROVISION OF MEANS FOR SUBJECTING THE OTHER SIDE OF PRESSURE-RESPONSIVE MEMBER TO UPSTREAM PRESSURE IN RESPONSE TO DOWNSTREAM PRESSURE INCREASING TO S A SELECTED VALUE. 